Exploding tape



Aug. 4, 1964 l Filed May 18, 1960 S. OSTROW EXPLODING TAPE 2 Sheets-Sheet l INVENTOR. STANL EY OSTROW Aug. 4, 1964 s. VosTRow EXPLOD'ING TAPE Filed May 18. 1960 2 .Sheets-Sheet 2 INVENTOR. STANLE Y osTRow' ATTYS.

United States Patent O 3,143,069 EXPLQDING TAPE o Stanley Ustrow, Silver Spring, Md., assignor to Electronic Research and Development Corporation, Washington,

D.C., a corporation of the District of Columbia Filed May i8, 1960, Ser. No. 30,037 3 Claims. (Ci. 102--2S) (Granted under Title 35, ILS. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to an exploding metallic tape of the type used to ignite compressed combustible gases.

An object of the present invention is to provide means by Which to ignite compressed combustible gases where such gases are confined Within a comparatively large chamber and where it is desirous that the ignition take place over the entire chamber simultaneously.

Another object of the invention is the provision of an igniting means for a compressed combustible gas which in the igniting process will be substantially consumed so that no residue having effective mass remains.

A further object of the invention is the provision of an explodable metallic tape having a length commensurate with the chamber containing compressed combustible gas which the explosion of the tape is to ignite and to form said tape so that the explosion of the tape occurs simultaneously at -a plurality of points along the length of the tape.

It is a still further object to provide an explodable metallic tape for igniting a compressed combustible gas, throughout the length of the chamber containing the gas, and to support the tape with a material cemented thereto which material will be consumed with the exploding tape so as to leave a residue of insignificant mass.

Other objects and many ofthe attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is an illustration of the application of the invention;

FIG. 2 is a top plan view of the tape;

PIG. 3 is a view similar to FIG. 2 taken at the time of ignition;

FIG. 4 is a section on line 4-4 of FIG. 2;

FIG. 5 is a section on line 5-5 of FIG. 2;

FIG. 6 is a sectional View of the tape holder; and

FIG. 7 illustrates a wiring diagram suitable for use with the present invention.

Referring to the drawings, FIG. 1 diagrammatically illustrates the object of the invention as applied in the apparatus in which it is used. A wind tunnel 11 has a model 12 mounted therein on a support 13. The model is exposed to a sudden blast of gases moving at supersonic velocity and measurements of the temperature and pressure are taken at different places on the model. High speed cameras (not shown) take pictures during this extremely short interval of time and the pictures are studied and analyzed. As the models are preferably missiles designed to travel in the upper atmosphere at supersonic speeds the importance of obtaining test data which accurately portrays the behavior of the model under simulated conditions existing in the atmosphere is of utmost importance. It is necessary, therefore, that the blast of gas be free of any particles of solid mass. The metals within the gun, the blowout valves, and the igniter support must be capable of withstanding heat and pressure. The tape itself must be completely consumed.

The blast of gases is generated in a gun 14 having a 3,143,069 g Patented Aug. 4., 1964 compression chamber 16 and a reduced barrel 1S which extends into the wind tunnel 11. Between the compression chamber 16 and the barrel 18 there is located a steel blowout diaphragm valve 19 which is scored and subject to bursting at a predetermined pressure. Since the details of valve 19 are not necessary to an understanding of the present invention, further description of the valve is believed unnecessary. A second similar diaphragm valve 21 is located at the termination of the gun, that is, at the end of the barrel and within the Wind tunnel.

The compression chamber 16 has a threaded breech 22 into which is turned a breech plug 23. The breech plug supports a rigid rod 24 in the threaded hole 26 which rod is secured to the plug by screw threads 27. At the free end of the rod a substantially triangular shaped rest 28 is welded or otherwise attached to the rod 24. The rest 28 is slotted at 25 to receive the end of the tape and a set screw 30 which turns entirely into the hole 35 holds the tape secured in the slot. The end is first secured in the slot and the tape folded over the set screw and stretched above the rod 24 to the xture 20 at the end of the breech plug 23.

Also carried in the breech plug is an insulator tube 31 and a cylindrical insulator plug 31 housing a contact rod 32 which carries the lixture 20. The tape 29 is secured to the fixture by a set screw 33.

The tape 29 is approximately three feet long, one-half inch wide and of the thinness of metal foil. Referring to FIGS. 2, 3 and 4, the metallic tape 29, preferably of aluminum, is formed with a plurality of notches 34 which leave reduced portions 36 of substantially one-fourth the width of the tape and in length less than the dimension of the width. The portions 36 provide areas of high resist- -ance to the passage of a high voltage electric current.

The tape is strengthened by a plastic tape 37 such as cellophane tape adhering to one side thereof. This tape is of a width and length equal to the greatest width and length of the tape and is uncut at the locations of the notches 34. The cellophane tape serves to support the metallic tape throughout its extent and particularly at the vreduced portions. The span of approximately three feet would probably break an unsupported metallic tape.

Referring to FIG. 7 a source of high voltage 38 is connected to a condenser 39, one side of which is grounded. The other side is connected through a switch 40 to the contact rod 32 of the breech plug.

In use, combustible gases in the nature of hydrogen, oxygen and helium are compressed in the chamber 16 by any suitable means and the switch 40 closed. The high voltage current from the condenser passes through the contact wire to the tape and produces a burning of the tape simultaneously at the reduced portions as illustrated in FIG. 3. This ignites the compressed gases simultaneously at a plurality of points throughout the extent of the gas chamber causing a rapid combustion. The pressure generated by the expanding gases bursts lthe diaphragm valve 19 and in turn the diaphragm valve 21 expanding into the wind tunnel at supersonic speed to buffet and impinge on the model 12 exerting pressure and causing temperature changes on and in the model.

Should there be any foreign particles in these expanding gases their contact with the model Would adversely effect the experiment. It is necessary that both the metallic tape and the supporting cellophane tape be entirely consumed or that such residue as is left have negligible mass.

The effects of the blast on the model are recorded and designs of the model altered and revised accordingly.

This type of igniter is necessary for the combustion desired to produce the correct expansion of gases, and to completely burn so that no appreciable residue is left.

Obviously many modifications `and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood, that Within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

What is claimed and desired to besecured by Letters Patent of the United States is:

1. The combination of a combustion-supported gaslled chamber, a ilexible metallic foil tape disposed in .Y

said chamber, and means for passing electrical current through said foil to initiate combustion thereof, said tape comprising a thinvstrip of aluminum foil having substantial width and relatively continuous running length, a plurality of equally sized notches disposed at equal igni- Ytion point intervals along the length of said tape, each of said notches extendng'inward Yfrom one and the same edge of the foil and reducing its width to a narrow bridging portion connecting the unnotched portions of the foil, the bridging portions each being of a size to be heated and burned simultaneously by passage of electrical current along the length of the tape.

2. An ignition tape comprising thin eXible aluminum foil having a substantially even width along its relatively continuous running length, and a combustible substantially lequally sized plastic tape disposed adjacent to a surface of said metal foil and adhering thereto as a exible continuous running support therefor, said aluminum foil tape having evenly sizednotches evenly spaced at desired ignition point intervals along its length, each notch extending inward from one'and the same side reducing the width of said tape to a relatively narrow bridging portion connecting the contiguous unnotched portions of said foil',

each bridging portion being reduced in Width by said notch suicient to be heated and burned simultaneously by the passage of electrical current along the length of said tape.

3. An elongated closed cylindrical chamber having a quantity of explosive gas under pressure stored therein, a thin metallic tape disposed axially Within said chamber substantially throughout the length thereof, comprising thin flexible aluminum foil having a substantially even width along its relatively continuous running length, and a combustible substantially equally sized plastic tape disposed adjacent to a surface of said metal foil and adhering thereto as a flexible continuous running support therefor, said aluminum foil tape having evenly sized notches evenly spaced at desired ignition point intervals along its length, each notch'extending inward from one side reducing the width of said tape to a relatively narrow bridging portion connecting the contiguous unnotched portions of said foil, each bridging portion being reduced in width by said notch sufficient to be heated and burned simul- Campbell Mar. 18, 1941 2,926,566 Atkins Mar. 1, 1960 FOREIGN PATENTS 578,300 Great Britain June 24, 1946 581,316 Canada Aug. 11, 1959 

1. THE COMBINATION OF A COMBUSTION-SUPPORTED GASFILLED CHAMBER, A FLEXIBLE METALLIC FOIL TAPE DISPOSED IN SAID CHAMBER, AND MEANS FOR PASSING ELECTRICAL CURRENT THROUGH SAID FOIL TO INTITIATE COMBUSTION THEREOF, SAID TAPE COMPRISING A THIN STRIP OF ALUMINUM FOIL HAVING SUBSTANTIAL WIDTH AND RELATIVELY CONTINUOUS RUNNING LENGTH, A PLURALITY OF EQUALLY SIZED NOTCHES DISPOSED AT EQUAL IGNITION POINT INTERVALS ALONG THE LENGTH OF SAID TAPE, EACH OF SAID NOTCHES EXTENDING INWARD FROM ONE AND THE SAME EDGE OF THE FOIL AND REDUCING ITS WIDTH TO A NARROW BRIDGING PORTION CONNECTING THE UNNOTCHED PORTIONS OF THE FOIL, THE BRIDGING PORTIONS EACH BEING OF A SIZE TO BE HEATED AND BURNED SIMULTANEOUSLY BY PASSAGE OF ELECTRICAL CURRENT ALONG THE LENGTH OF THE TAPE. 